Quoted from Sparky:

The things that come up the most when this question is asked are the following:
- Protection at the I&S saucer (there was a clear one, but I don't know if that's still being sold).
- Protector under the garage ramp (this ramp can crack and sag because of a lack of support underneath).
- Couch weld (problems with ball locks on the couch; my game has never had this problem, so I've never checked the details, but a lot of owners in this group talk about the fix).
Those are the most common issues. The other issues that come up seem to be issues that are not really specific to TSPP regarding switches not registering, blown transistors, VUK power, etc.
For add-ons, ColorDMD is probably your first mod priority.
If you're converting to LED, the OCD board will get rid of the ghosting, which is bad in this game.
Pinsound has gained popularity recently because of a few guys who have put together some really cool sound packages.
Tons of mods for this game.

Quoted from Spelunk71:

I was happy to see a TSPP on location in Ventura, CA during my travels today, but holy cow that thing was filthy! 75 percent of the lights were out. I couldn’t bring myself to play a game to see what nightmares lurk therein. So nice to see awesome pins on location, but so depressing to see them in such poor shape.[quoted image]